Tracking trajectories of the cart-pendulum system

The problem of tracking a periodic trajectory of the well-known cart-pendulum system is solved. After a change of coordinates and a change of feedback, the equations of this system are nonlinear but feedforward. This property is extensively used to carry out for this system the design of uniformly asymptotically stabilizing time-varying state feedbacks by using the forwarding approach.     

Superplasticity in a high strength powder aluminum

The superplastic properties of a rapidly solidified, high strength P/M Al alloy and the same alloy reinforced with SiC particulates (SiC _p ) have been studied. To prepare superplastic test materials, a matrix alloy powder of composition 7.2Zn-2.4Mg-2Cu-0.2Zr-0.12Cr-0.2Co (Kaiser PM-64) and the powder mixed with 10 to 20 vol pct SiC _p (~5 μm diameter) were thermomechanically processed to very fine equiaxed grain structures of ~6 μm and ~8 μm, respectively. Superplasticity in these materials was evaluated by characterizing (1) high temperature stability, (2) dynamic grain growth, (3) strain rate sensitivity, (4) flow stress behavior, (5) cavitation and cavitation control, and (6) total superplastic strain. It was observed that the PM-64 alloy could achieve a total elongation of over 800 pct, while the SiC_p reinforced alloy could attain an elongation greater than 500 pct before failure. Also, it was shown that with the use of hydrostatic pressure during superplastic flow, cavitation could be controlled. Observations were made of the effect SiC _p reinforcement particles had on the superplastic flow stress behavior. Interpretations are proposed to explain the role of particulates during superplastic straining.     

Pulse arithmetic in VLSI neural networks

This review explores the use of biological signaling methods to build silicon networks. Recent designs using a technique called `pulse stream', which employs fully analog, dynamic weight storage, are described. The pulse-stream concept is explained, and a comparison is made with conventional analog neural networks. An analog synapse based on the pulse-stream approach is presented. Chip details and simulation results are given     

A time aggregation approach to Markov decision processes

We propose a time aggregation approach for the solution of infinite horizon average cost Markov decision processes via policy iteration. In this approach, policy update is only carried out when the process visits a subset of the state space. As in state aggregation, this approach leads to a reduced state space, which may lead to a substantial reduction in computational and storage requirements, especially for problems with certain structural properties. However, in contrast to state aggregation, which generally results in an approximate model due to the loss of Markov property, time aggregation suffers no loss of accuracy, because the Markov property is preserved. Single sample path-based estimation algorithms are developed that allow the time aggregation approach to be implemented on-line for practical systems. Some numerical and simulation examples are presented to illustrate the ideas and potential computational savings.     

Memory scanning: Are fixed and varied sets scanned concurrently or successively?

Subjects were timed as they decided whether individually presented probe letters were or were not contained in pairs of memorized sets of one, two, or four letters. One set was fixed in advance of a block of trials, while the other varied from trial to trial. In Experiments 1 and 2, subjects responded positively if the probe was in either set and negatively otherwise; in Experiment 3 they made different responses to fixed-set, varied-set, and negative probes. In all three experiments, reaction time (RT) to varied-set probes depended more on the size of the varied set than of the fixed set, whereas RT to fixed-set and negative probes depended more on the size of the fixed set. These results were generally consistent with the hypothesis that scanning of the two sets was at least to some extent concurrent rather than successive, with the fixed set scanned more slowly than the varied set. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

THE QUEST FOR WORLD CLASS IT CAPABILITY IT Is Key to Achieving Quality Goals

In today's competitive world, many organizations are pursuing total quality improvement programs, and as a result of these initiatives, are seeking to define world class capabilities. The organizations with these aspirations are trying to improve product and service quality, business process quality, or delivered quality, and are becoming aware that information technology is playing a more substantial role in realizing these quality goals.     

Algorithm for finding all k nearest neighbors

A very simple algorithm for computing all k nearest neighbors in 2-D is presented. The method does not rely on complicated forms of tessellation, it only requires simple data binning for fast range searching. Its applications range from scattered data interpolation to reverse engineering.     

Scaffolded writing and rewriting in the discipline: A web-based reciprocal peer review system

This paper describes how SWoRD (scaffolded writing and rewriting in the discipline), a web-based reciprocal peer review system, supports writing practice, particularly for large content courses in which writing is considered critical but not feasibly included. To help students gain content knowledge as well as writing and reviewing skills, SWoRD supports the whole cycle of writing, reviews, back-reviews, and rewriting by scaffolding the journal publication process as its authentic practice model. In addition, SWoRD includes algorithms that compute individual reviewer’s review accuracy, which is in turn used to support the various drawbacks of reciprocal peer reviews (e.g., variation in motivation or ability of reviewers). Finally, this paper describes an empirical evaluation showing that the SWoRD approach is effective in improving writing quality in content classes.